But now, following the shooting at Sandy Hook Elementary School in Newtown, Conn., last December, a private school in Portland is joining the trend.

Cheverus High School has hired Portland Police Officer Kevin Haley to work full-time at the school, becoming the first private school in southern Maine to hire a police officer for security.

Rodger Cilley, vice president of student affairs at Cheverus, said hiring Haley was a direct response to the shooting at Sandy Hook.

"When Sandy Hook happened, obviously all schools got serious about security," he said. "(Haley is) the first line of defense. He's going to secure our facility like it's never been secured before."

But Cilley said Haley is also expected to play multiple roles at Cheverus.

"He's not here to jam the kids up. (He's) not here to bust and handcuff them and put them in a police car. If that happens, (it means) we've given them every opportunity to do the right thing," he said. "We do have the handcuffs, but that's not what we're about. It's about guidance, mentoring and leading these kids toward healthy habits."

Cilley said that although Haley only started work recently, having an officer at the school has already made a "quantitative difference in our school environment."

"I think the impact of having an actual police officer present in our building is an extraordinary message to the community that we are so serious and care so much about you that we want to protect you in every way," he said.

As a member of the city's Police Department, Haley already responded to calls at Cheverus as part of his beat, Portland Police Chief Michael Sauschuck said.

The department, like many throughout the state, frequently works with private schools to develop security plans and coordinate punishment, he said.

But this is the first time an officer has been hired full time and it's also the first time a private school has asked, Sauschuck said.

Officers are not typically hired directly by private businesses or organizations, but Sauschuck said because Cheverus is a school, it fits within the department's mission.

"These decisions have to be made in a way that match our procedures and policies," the chief said. "We would not be providing security work at a bank."

Cheverus also pays 100 percent of the cost for the police officer, unlike public schools, where the city shares 25 percent of the burden, Sauschuck said. Haley is paid "at the same rate as if he's working the street," the chief said, plus a school resource officer stipend.

While Cheverus has decided there is a need for police presence, no other private schools in the area have made that leap. School officials surveyed said they are continually developing security plans, but none have reached the conclusion that a full-time officer is necessary.

North Yarmouth Academy Head Brad Choyt said his Yarmouth school, like most other schools, is trying to strike a balance between safety and a healthy school culture.

"I'm saddened by the need of some school officials to increase the number of officers with firearms around children," Choyt said, noting that he doesn't want to judge other schools' decisions about safety because he's not familiar with their particular environments and situations.

"Is there a coorrelation to firearms and safety? Does it statistically make a campus more safe?," he said. "It could be that we think it's more safe, but in reality accidents happen everywhere."

Choyt said NYA was working with the Yarmouth police and fire departments on a "risk management" plan prior to the Sandy Hook shooting, and that the work continues today. He said they currently have no plan to hire a police officer.

"We take safety and security of students incredibly seriously and are continuing to evaluate the risk through our risk management committee at the school," he said.

Waynflete School, a private school in Portland's West End neighborhood, has talked with police about campus safety, but has decided not to hire a police officer at this point, Head of School Geoffrey Wagg said.

"We haven't gone down that road. I'm not sure if we've given enough time to that topic for it to be regular part of school life," Wagg, who took over leadership of the school last year, said. "I don't have sense that there's a large group advocating for it either. There's been no specific requests to have a full-time police officer (at Waynflete)."

Both Deborah Kost, of Catherine McAuley High School in Portland, and Christine Sloan, of the Merriconeag Waldorf School in Freeport, declined extended interviews. But both said their schools do not have any current plans to hire police officers.

Nationally since the Newtown shooting, there have been calls and legislation for more police and enhanced security systems in schools. One bill, introduced by U.S. Sen. Barbara Boxer, D-Calif., called for the installation of National Guard troops in schools.

That bill died, but the help of a cascade of federal funding for enhanced security, the number of police officers in public schools has grown dramatically since the 1990s. Local police and sheriff's offices employ more than 20,000 school resource officers nationwide, according to the Bureau of Justice Statistics of the U.S. Department of Justice's Office of Justice Programs.

In 2010, more than 40 percent of schools had assigned security staff and nearly 30 percent of that staff carried firearms, according to the BJS.

Studies on the subject of whether police officers make schools safer support multiple, sometimes overlapping theories and conclusions. Some research indicates one perhaps expected consequence: increased student arrests and citations for minor disturbances.

As police presence in schools increases, so does the number of school-reported crimes with weapons and drugs, as well as less-serious crimes, according to a 2011 research paper published by Chongmin Na and Denise Gottfredson, professors of criminology at the University of Houston and University of Maryland, respectively.

The authors argue that police in schools can lead to students being arrested for relatively minor behaviors that in the past typically would have been handled by school administration and teachers.

Another study, published earlier this month by University of Tennessee Professor Matthew Theriot, examined the impact of police officers on students.

While students generally had a positive view of school officers, Theriot's research indicates officers' interactions with students "were associated with lower levels of school connectedness" because the officers may increase student anxieties about threats of violence at school and about being arrested.

And now, with a strong push from the federal government for more police and tightened security, school culture hangs in the balance, Wagg said.

"Sandy (Hook) made all of us take a deep breath and ask 'are we doing enough and should we be doing more?'" he said. "What's the balance of safety and protections versus creating incredibly locked schools?

"Of course, that's what Sandy Hook was. They did everything their police jurisdiction told them to. ... I think that's the complexity of this issue."

In addition to adding a police officer, Cilley said Cheverus has also made the school more secure with locked doors and new protocols for allowing people to enter.

"We used to be a wide open school, and there's something nice and lovely and refreshing about that idea," he said. "Unfortunately the world has changed and we have to be proactive. We can't just do nothing."

"It does change the feel of things," Cilley continued. "It's a little sad that it changes it, but it's just part of who we are now."